Creating Websocket servers and clients in Nodejs

1. Websocket server example

const WebSocketServer = require('ws'); const wss = new WebSocketServer.Server({ port: 8111 }) wss.on("connection", (ws,r) => { ws.on("message", data => { ws.send('You sent me: ' + data); }); ws.on("close", () => { }); ws.onerror = function () { }; }); 

• require('ws') - import ws lib to create websocket server,
• new WebSocketServer.Server - create and launch websocket server with params,
• port: - port to listen on (in our case all network interfaces are going to be listened),
• wss.on("connection" - what to do when someone connects to our server,
• ws.on("message" - what to do when we've received a message from client,
• ws.send( - send a message to client,
• ws.on("close" - what to do when client closes connection,
• ws.onerror - set custom error handler.

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2. Websocket client example

let ws = require('websocket'); let wsc = new ws.client; wsc.on('connect', function(connection) { connection.sendUTF('Hello'); connection.on('message', function(message) { console.log("Received: " + message.utf8Data); // connection.close(); }); }); wsc.connect('ws://echoof.me:8111/'); 

• require('websocket') - import websocket lib to create websocket client,
• new ws.client - create new websocket client object,
• wsc.on('connect' - specify what to do when client gets connected to websocket server,
• connection.sendUTF - send message to server,
• connection.on('message' - specify what to do when client received message from server,
• connection.close() - close connection (and exit),
• wsc.connect - connect to websocket server,
• echoof.me:8111 - public echo websocket server.

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